The present invention relates to a semiconductor diode, and more particularly to a beta voltaic semiconductor diode fabricated from a radioisotope. Beta voltaics convert the energy of radioactive decay products directly into electrical power. They operate much the same way as a solar cell except that the beta particles (high energy electrons) are used, rather than photons. The beta particles can produce many electron-hole pairs in the diode per incident particle. The accepted method of construction is to coat a diode with a beta emitter (i.e. a radioisotope that undergoes beta decay) such as Nickel 63, tritium (usually as a metal hydride), or promethium 147. Radiation damage is often an issue, therefore silicon carbide, (being more radiation hard than silicon) is primarily used. The high energy electrons (beta particles) do not penetrate very far into silicon. This presents issues for fabrication of the diodes and favors high surface to volume geometries (i.e., pillar or comb structures are employed).